Originally offshore oil and gas wells were completed on platforms resting on the ocean bottom, or were completed on the bottom with surface production facilities installed on such a platform. Oil and gas produced at such platforms were either collected by tankers or by flowlines laid on the bottom. To the extent that underwater work was required, it was performed by divers, by submarines, or by simple manipulations from the surface.
More recently it has become necessary to drill oil and gas wells in water which is too deep or too dangerous for convenient underwater operations by divers or for platforms standing on the bottom. It has thus become necessary to devise methods of connecting subsea oil and gas wells at the ocean floor with flowlines, hydraulic control lines and electrical cables extending to the surface without the use of divers or any permanent surface structure adjacent the underwater well. Various devices have been proposed for achieving such underwater connections, as shown for example in U.S. Pat. Nos. 3,968,838 to Baugh, 4,019,334 to Sinclair, et al, and 4,086,778 to Latham, et al. A better understanding of the problems presented may be obtained by reference to the January 1978 issue of Offshore Services magazine, published by Spearhead Publications Limited, at pages 26-51.
In connecting, by remote operation, flowlines and hydraulic lines to an underwater production unit, it is essential to insure that the connection is properly sealed. One or more of the hubs or ends of the lines may become damaged during their descent to the ocean bottom, travel along the ocean floor, and pulling onto the production unit for connection thereto. Such damage may prevent sealing engagement with the hub on the production unit.
In the past clamp connectors for underwater flowline assemblies, such as the one disclosed in applicants' own prior patent, U.S. Pat. No. 3,843,168 to Morrill, et al, have not used seal plates between the hubs but merely clamped the hub faces together to achieve fluidtight engagement. Hence, the hub alignment is critical prior to clamping and sometimes the connection could not be tested hydraulically before full flow conditions are established. Other connections include elongated spool pieces, such as the one disclosed in U.S. Pat. No. 4,019,334 to Sinclair, et al, which require two clamps or sets of bolted flanges, one at each end of the spool piece, to establish a fluidtight connection.
Prior art connections require direct end-to-end alignment between mating flowline and hydraulic control line ends and do not permit fluid interconnection between one line and any other line not directly aligned with each other without physically rearranging or realigning the lines within the connection.
The present invention overcomes the deficiencies of the prior art by providing a seal plate between the ends of lines in the connection. The seal plate eliminates critical hub alignment, provides improved sealing, permits testing of the connection and allows rerouting of flow between the various lines. Other objects and advantages of the present invention will appear from the following description.